• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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• pp.781-784
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• 1993

Most linguistic models of processes or plants known are essentially static, that is, time is not a parameter in describing the behavior of the object's model. In this paper we show two models for synchronous finite state machines (FSM) based on fuzzy logic, namely the Crisp-State-Fuzzy-Output (CSFO FSM) and Fuzzy-State-Fuzzy Output (FSFO FSM). As a result of the introduction of the FSM models, the improved architectures for fuzzy logic controller have been defined. These architectures featuring pipelined intelligent fuzzy controller are discussed in terms of dimensionality of the model. VLSI integrated circuit implementation issues of the fuzzy logic controller are also considered. The presented approach can be utilized for fuzzy controller hardware accelerators intended to work in the real-time environment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1051-1053
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• 2003

Flywheel Energy Storage System (FESS) consists of a high-speed flywheel with an integral motor/generator suspended on magnetic bearings and in an evacuated housing. Permanent magnet (PM) machines as the FESS motor/generator are a popular choice. since there are no excitation losses which mean substantial increase in the efficiency. In this paper, the basic design and the steady-state performances of a permanent magnet synchronous high speed motor/generator for FESS are presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.189-191
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• 1993

A systematic procedure for the elements of system matrix in multimachine systems with loads is suggested for the small-signal stability studies. Synchronous machines are represented by either a two-axis model or classical model. The interrelationship of submatrices of system matrix is investigated. Once elements of one submatrix are determined, they can be used to calculate the elements of the other submatrix. It is illustrated for three machine and nine bus multimachine systems with constant impedance loads, constant MVA load, constant current and power factors.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1072-1074
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• 1993

The superconducting generator has better efficiency, larger power, higher voltage, bigger power per weight ratio and bigger power per volume ratio than conventional machines. Furthermore, for the synchronous reactance of the superconducting generator is smaller than that of conventional ones, the capacity of power transfer is much larger than conventional machina. But, the low inertia constant of superconducting generator hurts the transient stability of power system. This paper deals with the comparisons of transient characteristics between superconducting generator and conventional generator by computer simulation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.162-168
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• 2008

To predict efficiency of Interior Permanent Magnet Synchronous Motors(IPMSM) and to cope with the demagnetization risk of permanent magnets used in the IPMSM, accurate iron analysis of the IPMSM is very important at the motor design stage. In the analysis, we developed a new iron loss model of electrical machines for high-speed operation. The calculated iron loss was compared with the experimental data. It was clarified that the proposed method can estimate iron loss effectively at high-speed operation.

• Journal of Power Electronics
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• 제10권5호
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• pp.548-554
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• 2010

In this paper, a 1.5 kW Interior Permanent Magnet Synchronous Generator (IPMSG) with a power conditioner for the grid integration of a variable-speed wind turbine is developed. The power-conditioning system consists of a series-type 12-pulse diode rectifier powered by a phase shifting transformer and then cascaded to a PWM voltage source inverter. The PWM inverter is utilized to supply sinusoidal currents to the utility line by controlling the active and reactive current components in the q-d rotating reference frame. While the q-axis active current of the PWM inverter is regulated to follow an optimized active current reference so as to track the maximum power of the wind turbine. The d-axis reactive current can be adjusted to control the reactive power and voltage. In order to track the maximum power of the wind turbine, the optimal active current reference is determined by using a simple MPPT algorithm which requires only three sensors. Moreover, the phase angle of the utility voltage is detected using a simple electronic circuit consisting of both a zero-crossing voltage detecting circuit and a counter circuit employed with a crystal oscillator. At the generator terminals, a passive filter is designed not only to decrease the harmonic voltages and currents observed at the terminals of the IPMSG but also to improve the generator efficiency. The laboratory results indicate that the losses in the IPMSG can be effectively reduced by setting a passive filter at the generator terminals.

• International Journal of Automotive Technology
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• 제4권2호
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• pp.87-94
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• 2003

Recent advancements of permanent magnet (PM) materials and solid-state devices have contributed to a substantial performance improvement of permanent magnet machines. Owing to the rare-earth PMs, these motors have higher efficiency, power factor, output power per mass and volume, and better dynamic performance than induction motors without sacrificing reliability. Not surprisingly, they are continuously receiving serious considerations for a variety of automotive and propulsion applications. An electric vehicle (EV) requires a high-effficient propulsion system having a wide operating range and a capability of generating a high peak torque for short durations. The improvement of torque-speed performance for these systems is consequently very important, and researches in various aspects are therefore being actively pursued. A great emphasis has been placed on the efficiency and optimal utilization of PM machines. This requires attention to many aspects related to the machine design and overall performance. In this respect, the prediction of iron losses is particularly indispensable and challenging, especially for drives with a deep field-weakening range. The objective of this paper is to present iron loss estimations of a PM motor over a wide speed range. As aforementioned, in EV applications core losses can be significant during high-speed operation and it is imperative to evaluate these losses accurately and take them into consideration during the motor design stage. In this investigation, the losses are predicted by using an analytical model and a 2D time-stepped finite element method (FEM). The results from different analytical approaches are compared with the FEM computations. The validity of each model is then evaluated by these comparisons.

• 한국산학기술학회논문지
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• 제19권3호
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• pp.69-74
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• 2018

산업현장에서 사용되는 대형 모터는 전기자권선의 절연내력 저하 및 과열문제 등으로 인하여 정지사고의 위험이 높고 산업재해의 규모가 크므로 넓은 장소의 확보가 필요하다. 따라서 기존 모터에 비해 소형, 경량이면서 절연내력이 뛰어난 대용량 모터가 요구되어지고 있으며 이에 대한 연구가 활발히 진행되어지고 있다. 초전도 모터는 기존의 발전기나 모터와 같은 회전기의 계자코일을 초전도 화하여 계자의 발생을 크게 증가시킴으로서, 기기의 효율과 출력을 높이고, 소형화 및 경량화, 안정도 향상 등의 장점을 가지고 있으므로 초전도 선재의 성능을 발휘할 수 있도록 선제의 임계온도 이하로 낮추어줄 수 있는 냉각시스템의 설계 및 해석기술이 매우 중요하다. 따라서 본 연구에서는 100HP 고온초전도 동기모터의 개념설계를 통한 계자손실 해석과 냉각시스템의 저온 열전달 해석을 수행하였다. 계자손실 해석 결과, 고온초전도 선재를 사용하게 되면 균일한 공극자속밀도가 나타남을 확인하였다. 그리고 가스네온 및 액체네온에 대한 저온 열전달 해석 결과, 고온초전도 선재의 저온 안정성을 유지하기 위해서는 액체네온 1kg/min의 유량의 사용이 적합함을 확인하였다.

• 한국정밀공학회지
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• 제19권11호
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• pp.221-227
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• 2002

Tapping is a machining process that makes a female screw on parts to be assembly together. Recently, as the number of small and compact products increases the radius of tap as small as 1 mm is not unusual and more accurate tapping is needed. In complying with those needs, some high-speed tapping machines with synchronizing function have been developed. This paper describes the development of an ultra high-speed tapping machine up to 10,000rpm. The key factors in the tapping speed are the acceleration/deceleration and the synchronizing errors between spindle motor and fred motor. To minimize the acceleration/deceleration time, a low inertia spindle with a synchronous built-in servo motor was developed. To minimize the synchronizing errors, the tapping cycle algorithm was optimized on an open architecture CNC. The developed tapping machine has the acceleration/deceleration time of 0.13sec/10,000rpm for rigid tapping and the synchronizing error below 4.4%. The cycle time for tapping a female screw of M3 and depth 2 times diameter was 0.55sec.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.848-849
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• 2011

Rotating machines are using gears to change the rotary motion into the linear motion, on the other hand, linear motors have a accurate position control and excellent dynamic characteristics because of generating a thrust force directly. But the important problem, one of the linear motor is a high thrust force ripple. Thrust force ripple has a bad effect on the position accuracy and the dynamic characteristics, so it is necessary to reduce the thrust force ripple. Cogging is one of the cause that affect thrust force ripple. Cogging has some connection with the GCD between pole pitch and teeth pitch It is proposed method to reduce a thrust ripple of the linear motor that chamfering, skew, and so on. In this paper, the module phase set shift(MPSS) is used to reduce a thrust force ripple that has a similar effect to skew. And propose a method that reduce a thrust force ripple more by use of chamfering.